Russell Simmons is the most important businessman in the history of rap music. As co-founder of the Def Jam label, Simmons' street-friendly taste and marketing savvy helped bring hip-hop crashing into the mainstream of American culture and mass media. He's often been compared to Motown impresario Berry Gordy, but there's one important difference: Where Gordy strove to make assimilationist R&B that would be considered respectable by pop audiences, Simmons ensured that his artists remained as uncompromisingly rebellious as possible. That attitude made hip-hop a music of choice f...